G
L O S S A R Y

Simple one-celled or many-celled micro-organisms capable of carrying
on photosynthesis in aquatic ecosystems.

Anoxia

The absence of oxygen necessary for sustaining most life. In aquatic
ecosystems, this refers to the absence of dissolved oxygen in water.

Area of Concern

An area recognized by the International Joint Commission where 1 or
more of 14 beneficial uses are impaired or where objectives of the Great
Lakes Water Quality Agreement or local environmental standards are not
being achieved.

Atmospheric Deposition

Pollution from the atmosphere associated with dry deposition in the
form of dust, wet deposition in the form of rain and snow, or as a result
of vapor exchanges.

Biochemical Oxygen Demand

The amount of dissolved oxygen required for the bacterial decomposition
of organic waste in water.

Biomagnification

A cumulative increase in the concentration of a persistent substance
in successively higher trophic levels of the food chain (i.e., from algae
to zooplankton to fish to birds).

Biomass

Total dry weight of all living organisms in a given area.

Biomonitoring

The use of organisms to test the acute toxicity of substances in effluent
discharges as well as the chronic toxicity of low-level pollutants in the
ambient aquatic environment.

Carcinogen

Cancer-causing chemicals, substances or radiation.

Consumptive Use

Permanent removal of water from a water body. Consumptive use may be
due to evaporation or incorporation of water into a manufactured product.

DDT

Dichloro-diphenyl-trichloroethane - a widely used, very persistent
pesticide in the chlorinated hydrocarbon group, now banned from production
and use in many countries.

Dissolved Oxygen

The amount of oxygen dissolved in water. See Anoxia and Biochemical
Oxygen Demand.

Diversion

Transfer of water from one watershed to another.

Drainage Basin

A waterbody and the land area drained by it.

Ecosystem

The interacting complex of living organisms and their non-living environment.

The warm, upper layer of water that occurs in a lake during summer
stratification.

Erosion

The wearing away and transportation of soils, rocks and dissolved minerals
from the land surface or along shorelines by rainfall, running water, or
wave and current action.

Eutrophication

The process of fertilization that causes high productivity and biomass
in an aquatic ecosystem. Eutrophication can be a natural process or it
can be a cultural process accelerated by an increase of nutrient loading
to a lake by human activity.

Exotic Species

Species that are not native to the Great Lakes and have been intentionally
introduced or have inadvertently infiltrated the system.

Food Web

The process by which organisms in higher trophic levels gain energy
by consuming organisms at lower trophic levels.

Human Health

The state of complete physical, mental and social well-being and not
merely the absence of disease or infirmity (World Health Organization).

Hydrologic Cycle

The natural cycle of water on earth, including precipitation as rain
and snow, runoff from land, storage in lakes, streams, and oceans, and
evaporation and transpiration (from plants) into the atmosphere.

Hypolimnion

The cold, dense, lower layer of water that occurs in a lake during
summer stratification.

Leachate

Materials suspended or dissolved in water and other liquids, usually
from waste sites, which percolate through soils and rock layers.

Mass Balance

An approach to evaluating the source, transport and fate of contaminants
entering a water system as well as their effects on water quality.

Mesotrophic

See Trophic Status

Monoculture

Agriculture that is based on a single type of crop.

Nonpoint Source

Source of pollution in which pollutants are discharged over a widespread
area or from a number of small inputs rather than from distinct, identifiable
sources.

Nutrient

A chemical that is an essential raw material for the growth and development
of organisms.

Oligotrophic

See Trophic Status

Pathogens

Disease-causing agents such as bacteria, viruses and parasites.

PCBs - polychlorinated biphenyls

A class of persistent organic chemicals that bioaccumulate.

Photosynthesis

A process occurring in the cells of green plants and some micro-organisms
in which solar energy is transformed into stored chemical energy.

Phytoplankton

Minute, microscopic aquatic plant life (see Alga).

Point Source Pollution

A source of pollution that is distinct and identifiable, such as an
outfall pipe from an industrial plant.

Productivity

The conversion of sunlight and nutrients into plant material through
photosynthesis, and the subsequent conversion of this plant material into
animal matter.

Resuspension (of sediment)

The remixing of sediment particles and pollutants back into the water
by storms, currents, organisms and human activities such as dredging or
shipping.

Seiche

An oscillation in water level from one end of a lake to another due
to rapid changes in winds and atmospheric pressure. Most dramatic after
an intense but local weather disturbance passes over one end of a large
lake.

Stratification (or Layering)

The tendency in deep lakes for distinct layers of water to form as
a result of vertical change in temperature and therefore in the density
of water. See also Epilimnion, Hypolimnion, Thermocline

Thermocline

A layer of water in deep lakes separating the cool hypolimnion (lower
layer) from the warm epilimnion (surface layer).

Toxic Substance

As defined in the Great Lakes Water Quality Agreement, any substance
that adversely affects the health or well-being of any living organism.

Trophic Status

A measure of the biological productivity in a body of water. Aquatic
ecosystems are characterized as oligotrophic (low productivity), mesotrophic
(medium productivity) or eutrophic (high productivity).

Wind Set-up

A local rise in water levels caused by winds pushing water to one side
of a lake.

Allardice, D., and S. Thorp. State of the Lakes Ecosystem Conference
Working Paper: A Changing Great Lakes Economy: Economic and Environmental
Linkages. Environment Canada and United States Environmental Protection
Agency, 1994.

Allen, Robert. The Illustrated Natural History of Canada: The Great
Lakes. Toronto: McClelland and Stewart, 1970.

Health and Welfare Canada. Having Your Catch and Eating it Too:
A Few Words About Sport Fish and Your Health. Great Lakes Health Effects
Program. Ottawa: Supply and Services Canada, 1992.

Health and Welfare Canada. A Vital Link: Health and the Environment
in Canada. Ottawa: Supply and Services Canada, 1992.

Hough, J.L. The Geology of the Great Lakes. University of Illinois
Press, 1958.

International Joint Commission. An Environmental Management Strategy
for the Great Lakes System. Final Report, International Reference Group
on Great Lakes Pollution from Land Use Activities (PLUARG). Windsor, Ontario,
1978.

International Joint Commission. Great Lakes Diversions and Consumptive
Uses. Report by the International Great Lakes Diversion and Consumptive
Uses Study Board, 1981.

International Joint Commission. Report on Great Lakes Water Quality.
Report of the Great Lakes Water Quality Board. Presented at Kingston, Ontario,
1985.

International Joint Commission. Revised Great Lakes Water Quality
Agreement of 1978 as Amended by Protocol Signed November 18, 1987.

J. Manno, et al. State of the Lakes Ecosystem Conference Working
Paper: Effects of Great Lakes Basin Environmental Contaminants On Human
Health. Environment Canada and United States Environmental Protection
Agency, 1994.

State of the Lakes

An Atlas of Contaminants in Eggs of Fish-Eating Colonial Birds of the
Great Lakes (1970-1988 and 1989-1992), Vol. I and Vol. II. Environment
Canada, Canadian Wildlife Service.

Government of Canada. Toxic Chemicals in the Great Lakes and Associated
Effects: Vol. I and Vol. II. Ottawa: Supply and Services Canada, 1991.

Neilson, M., et al. State of the Lakes Ecosystem Conference Working
paper: Nutrients: Trends and System Response. Environment Canada and United
States Environmental Protection Agency, 1994.

Ecoregions, Drainage Basins and Wetlands

Ecodistricts of Southern Canada, draft maps, 1/2,000,000, no date.

Ecoregions of the coterminous United States, maps, 1:7,500,000 by James
Omernik, Corvallis Environmental Research Laboratories, U.S. EPA, 1986.

International Reference Group on Great Lakes Pollution from Land Use
Activities, Inventory of Land Use and Land Use Practices in the Canadian
Great Lakes Basin, Vol. 1. Windsor: International Joint Commission, 1977.